Method for treating dermatitis and related conditions

ABSTRACT

Methods and pharmaceutical compositions for the treatment of dermatitis are disclosed. 2,3-diaryl-1-benzopyrans and their pharmaceutically acceptable salts are formulated into medicaments, including oral and topical medicaments, which are administered to a patient suffering from dermatitis. The methods and compositions are particularly useful in the treatment of conditions characterized by hyperproliferation of keratinocytes, such as psoriasis.

BACKGROUND OF THE INVENTION

Dermatitis encompasses a number of conditions characterized by reddishskin lesions that can develop into scaly, thickened plaques. Theselesions can arise from any of several primary causes, including contactwith allergens, ultraviolet light or chemicals, systemicallyadministered drugs, or localized trauma (irritation). The causes ofcertain forms of dermatitis are unknown.

Eczematous dermatitis refers to a group of conditions characterized inthe initial stages by edematous, oozing plaques that often containblisters. These lesions are prone to bacterial infection. Fluid leaksinto the intercellular spaces in the epidermis, giving it a spongyappearance. Over time, oozing diminishes, and the lesions become scalyas the epidermis thickens (epidermal hyperplasia).

Of particular concern are chronic forms of dermatitis, includingpsoriasis and the chronic stages of eczematous dermatitis. Psoriasis ischaracterized by round, thick, dry, reddish patches covered with silveryscales. Psoriasis may be localized or generalized, and in the lattercase may become life-threatening. Psoriatic lesions show markedepidermal hyperplasia and hyperproliferation of keratinocytes. Theetiology of psoriasis is believed to include hereditary and autoimmunecomponents. Chronic lesions of eczematous dermatitis are clinically andhistologically similar to psoriatic plaques.

Cellular proliferation (e.g. proliferation of keratinocytes) isregulated in part by intracellular calcium levels. Changes inintracellular calcium concentrations influence the phosphorylation ofproteins, thus influencing proliferation and other cellular processes.One of the molecules that mediates the effect of intracellular calciumlevels on protein phosphorylation is calmodulin, a protein co-factor forprotein kinase C.

Psoriasis is treated by the application of corticosteroids, coal tarointments, or anthralin. These treatments are only partially effectiveand may merely contain, not reverse, the disease. Anthralin may causeirritation, and its safety in children and pregnant women has not beenestablished. Corticosteroids have a number of undesirable side effects,including edema and mineral imbalances. Non-steroidal anti-inflammatoryagents are generally not effective.

Certain substituted 2,3-diaryl-1-benzopyrans have been shown to haveantiestrogenic activity with little or no estrogenicity, and have beenproposed for use in the treatment of breast cancer. See Kapil et al.,U.S. Pat. No. 5,254,568; Saeed et al., J. Med. Chem. 33: 3210-3216,1990; Sharma et al., J. Med. Chem. 33: 3222-3229, 1990; and Sharma etal., J. Med. Chem. ..33: 3216-3222, 1990. These compounds have notpreviously been shown to have anti-inflammatory properties or to beeffective against dermatitis.

There remains a need in the art for treatments for dermatitis that areeffective and lack serious side effects. The present invention addressesthis need and provides other, related advantages.

DISCLOSURE OF THE INVENTION

Within one aspect, the present invention is directed to methods fortreating dermatitis (including psoriasis), including the chronic stagesof these conditions, which are characterized by the hyperproliferationof keratinocytes. The present invention makes use of compounds of theformula I: ##STR1## wherein each of R1 and R2 is individually H, OH,linear or branched chain C₁ -C₁₇ alkoxy, linear or branched chain C₂-C₁₈ acyloxy, or linear or branched chain C₂ -C₁₈ alkoxycarbonyl; and R3is ##STR2## wherein each of R4 and R5 is individually a linear orbranched chain alkyl radical of from one to 18 carbon atoms, or togetherwith N, R4 and R5 form a three- to 10-membered ring, and n is an integerfrom 1 to 6.

Within one embodiment, the present invention provides a method fortreating eczematous dermatitis comprising administering to a patientsuffering from eczematous dermatitis an effective amount of acomposition comprising a compound of formula I or a pharmaceuticallyacceptable salt thereof in combination with a pharmaceuticallyacceptable carrier.

Within a related embodiment, the present invention provides a method fortreating psoriasis comprising administering to a patient a compositioncomprising a compound of formula I or a pharmaceutically acceptable saltthereof as described above.

Within another aspect, the present invention provides a method forinhibiting the proliferation of keratinocytes in a patient. Briefly, acompound of formula I or a pharmaceutically acceptable salt thereof incombination with a pharmaceutically acceptable carrier is administeredto a patient in an amount sufficient to inhibit keratinocyteproliferation.

Yet another aspect of the present invention provides a method forinhibiting calmodulin activity in a patient comprising administering tothe patient a compound of formula I or a pharmaceutically acceptablesalt thereof in combination with a pharmaceutically acceptable carrierin an amount sufficient to inhibit calmodulin activity.

These and other aspects of the invention will become evident uponreference to the following detailed description and the attacheddrawing.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE illustrates the preparation of certain compounds usefulwithin the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides methods for treating dermatitis(including psoriasis), including the chronic stages of these conditions,which are characterized by the hyperproliferation of keratinocytes. Thepresent invention makes use of 2,3-diaryl-1-benzopyrans, which aredefined by the general formula I: ##STR3## wherein each of R1 and R2 isindividually H, OH, linear or branched chain C₁ -C₁₇ alkoxy, linear orbranched chain C₂ -C₁₈ acyloxy, or linear or branched chain C₂ -C₁₈alkoxycarbonyl; and R3 is ##STR4## wherein each of R4 and R5 isindividually a linear or branched chain alkyl radical of from one to 18carbon atoms, or together with N, R4 and R5 form a three- to 10-memberedring; and n is an integer from 1 to 6, preferably 1 to 3, mostpreferably 1. Preferably, each of R4 and R5 is individually methyl,ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl or tert-butyl, ortogether with N, R4 and R5 form a five- or six-membered ring. Mostpreferably, R3 is ##STR5## Within preferred embodiments, the compounds Ihave the structure: ##STR6## Within other preferred embodiments, R1 andR2 are alkoxy. Within other preferred embodiments, R1 and R2 areindividually H, OH or C₁ -C₄ alkoxy, C₂ -C₅ alkoxycarbonyl or C₂ -C₅acyloxy. R3 is preferably a 2-piperidinoethoxy radical. Within otherpreferred embodiments, R1 and R2 are individually H or OH. As usedherein, the term "acyloxy" refers to radicals of the structure ##STR7##wherein R' is linear or branched chain alkyl or aminoalkyl.

Particularly preferred compounds for use within the present inventioninclude: ##STR8## i.e. R1═R2═H and R3 is: ##STR9## i.e. R1═OH, R2═H, andR3 is: ##STR10## i.e. R1═H, R2═OH, and R3 is: ##STR11## i.e. R1═R2═OHand R3 is: ##STR12##

Although it is preferred to use the 2,3-diaryl-2H-1-benzopyransdisclosed above, 2,3-diaryl-1-benzopyrans substituted at the 2 positionmay also be used to treat dermatitis and related conditions. Preferredsubstitutions in this regard include methyl, ethyl, propyl and butyl. Inaddition, each of the aromatic rings of I can be further substituted atone or more positions with a moiety such as OH; fluoro; CF₃ ; CN; alinear alkyl, alkoxy or acyloxy radical of from one to eighteen carbonatoms; a branched alkyl, alkoxy or acyloxy radical of from three toeighteen carbon atoms; NO₂ ; NH₂ or NHCOR", wherein R" is a linear orbranched chain alkyl radical of from one to eighteen carbon atoms. Thoseskilled in the art will recognize that substitutions should generally belimited in number and/or size so as not to disrupt the function of themolecule due to large changes in solubility, receptor interactions,biological activity, etc. Thus, substitutions are preferably limited innumber and will consist of groups of smaller size, e.g. lower (C₁ -C₄)alkyl radicals.

Benzopyrans of the formula I can be prepared according to the methodsdisclosed in Saeed et al., J. Med. Chem. 33: 3210-3216, 1990; Sharma etal., J. Med. Chem. 33: 3222-3229, 1990; and U.S. Pat. No. 5,254,568,which are incorporated herein by reference in their entirety. Arepresentative synthetic scheme is illustrated in FIG. 1. Base-catalyzedcondensation of desoxybenzoin II with 4-hydroxybenzaldehyde yields amixture of the dihydro-4H-1-benzopyran-4-one IV and the 2-phenylchalconeVI. Similarly, condensation of desoxybenzoin III with4-hydroxybenzaldehyde gives a mixture of the dihydrobenzopyran-4-one Vand the 2-phenylchalcone VII. Reduction of the phenylchalcones VI andVII with sodium borohydride followed by thermal cyclodehydration of thealcohols yields the 2H-benzopyran phenols VIII and IX, respectively.Compounds VIII and IX are then alkylated to produce the ethers X and XI,respectively. Hydroxy derivatives of I (i.e. those in which at least oneof R1 and R2 is OH) can be prepared as disclosed by Sharma et al.(ibid.) and in U.S. Pat. No. 5,254,568 by condensation of appropriatelyOTHP (O-tetrahydropyranyl) protected hydroxy derivatives ofdesoxybenzoin with 4-hydroxybenzaldehyde. Phenolic derivatives having apiperidinoethoxy residue on 2-phenyl are prepared by starting from THPethers of the appropriate desoxybenzoins, thereby allowing selectivityin attachment of the side chain to the requisite OH group.

Synthesis of 2,3-diaryl-1-benzopyrans substituted at one or morepositions on the aromatic rings is carried out using conventionalsynthetic techniques from suitable precursors, e.g. substituteddesoxybenzoins and/or substituted benzaldehydes, such as4-hydroxy-3-methoxybenzaldehyde, 3,4-dihydroxybenzaldehyde, or2,4-dihydroxybenzaldehyde.

Within the present invention, 2,3-diaryl-1-benzopyrans may be preparedin the form of pharmaceutically acceptable salts, especiallyacid-addition salts, including salts of organic acids and mineral acids.Examples of such salts include salts of organic acids such as formicacid, acetic acid, propionic acid, glycolic acid, lactic acid, pyruvicacid, oxalic acid, succinic acid, malic acid, tartaric acid, citricacid, benzoic acid, salicylic acid and the like. Suitable inorganicacid-addition salts include salts of hydrochloric, hydrobromic, sulfuricand phosphoric acids and the like. The acid addition salts may beobtained as the direct products of compound synthesis. In thealternative, the free base may be dissolved in a suitable solventcontaining the appropriate acid, and the salt isolated by evaporatingthe solvent or otherwise separating the salt and solvent.

According to the present invention, the 2,3-diaryl-1-benzopyrans andtheir salts are used within human and veterinary medicine for thetreatment of eczematous dermatitis and psoriasis. "Eczematousdermatitis" includes allergic contact dermatitis, atopic dermatitis,photoeczematous dermatitis and primary irritant dermatitis. The methodsof the present invention may be used to treat these conditions in theiracute or chronic stages. While not wishing to be bound by theory, it isbelieved that the therapeutic effect of the 2,3-diaryl-1-benzopyrans isat least in part due to an antagonistic effect on calmodulin, makingthese compounds particularly effective in the chronic,hyperproliferative stages of eczematous dermatitis and psoriasis.

For use within the present invention, 2,3-diaryl-1-benzopyrans and theirpharmaceutically acceptable salts are formulated with a pharmaceuticallyacceptable carrier to provide a medicament for topical or oraladministration according to conventional methods. Formulations mayfurther include one or more diluents, fillers, emulsifiers,preservatives, buffers, excipients, etc. and may be provided in suchforms as liquids, ointments, salves, gels, emulsions and the like. Oneskilled in the art may formulate the compounds in an appropriate manner,and in accordance with accepted practices, such as those disclosed inRemington's Pharmaceutical Sciences, 18th ed., Gennaro, ed., MackPublishing Co., Easton, Pa., 1990 (which is incorporated herein byreference in its entirety.) Such compositions may further include one ormore auxiliary substances, such as wetting agents, stabilizers,colorings, penetration enhancers, etc.

Within a preferred embodiment, pharmaceutical compositions are appliedtopically to skin lesions. Suitable compositions in this regard includeoil-based formulations such as ointments, water-in-oil emulsions andsolutions of the active agent in a volatile solvent such as anethanol/ether mixture. Compositions of this type are applied from one toseveral times daily. Water-based formulations may be applied as wetdressings.

The pharmaceutical compositions may also be administered orally,preferably as tablets or capsules. Oral administration will generallytake place at daily to weekly intervals.

An "effective amount" of such a pharmaceutical composition is the amountthat provides a clinically significant improvement in the symptoms ofthe condition to be treated. In particular, it is desirable to achieve areduction in epidermal hyperplasia and/or keratinocytehyperproliferation. Determination of such amounts will generally be doneempirically and is within the ordinary level of skill in the art. Thetreatment may be adjusted as necessary to obtain the desired effects,such as by altering the concentration of active ingredient in theformulation or by varying the treatment schedule. The actual amountadministered will of course depend in part on the particular conditionto be treated (including its extent and severity), age, weight, andgeneral health of the patient, and other factors evident to thoseskilled in the art. For example, a typical formulation for topicaldelivery will contain from 0.01 to 10 weight percent of a2,3-diaryl-1-benzopyran in a suitable vehicle, more preferably from 0.5to 5 weight percent. The formulation will be applied to the affectedskin from one to several times per day until the desired improvement isachieved.

General guidance for treatment regimens is obtained from experimentscarried out in animal models of the disease of interest. For example,animal models of psoriasis include the analysis of histologicalalterations in adult mouse tail epidermis (Hofbauer et al, Brit. J.Dermatol. 118: 85-89, 1988; Bladon et al., Arch Dermatol. Res. 277:121-125, 1985, incorporated herein by reference). In this model,anti-psoriatic activity is indicated by the induction of a granularlayer and orthokeratosis in areas of scale between the hinges of thetail epidermis. Typically, a topical ointment is applied daily for sevenconsecutive days, then the animal is sacrificed, and tail skin isexamined histologically. An additional model is provided by graftingpsoriatic human skin to congenitally athymic (nude) mice (Krueger etal., J. Invest. Dermatol. 64:307- 312, 1975, incorporated herein byreference). Such grafts have been shown to retain the characteristichistology for up to eleven weeks. As in the mouse tail model, the testcomposition is applied to the skin at predetermined intervals for aperiod of one to several weeks, at which time the animals are sacrificedand the skin grafts examined histologically. A third model has beendisclosed by Fretland et al. (Inflammation 14: 727-739, 1990;incorporated herein by reference). Briefly, inflammation is induced inguinea pig epidermis by topically applying phorbol ester(phorbol-12-myristate-13-acetate; PMA), typically at ca. 2 g/ml inacetone, to one ear and vehicle to the contralateral ear. Test compoundsare applied concurrently with the PMA, or may be given orally.Histological analysis is performed at 96 hours after application of PMA.This model duplicates many symptoms of human psoriasis, including edema,inflammatory cell diapedesis and infiltration, high LTB₄ levels andepidermal proliferation.

Calmodulin activity is conveniently assayed by measuring the activity ofcalmodulin-dependent enzymes. See, for example, Blumenthal et al.,Biochem. Biophys. Res. Comm. 156: 860-865, 1988, which is incorporatedherein by reference. Calmodulin-dependent enzymes include phosphorylasekinase, brain multifunctional calmodulin-dependent protein kinase andcalmodul-independent protein phosphatase (calcineurin). Phosphorylasekinase activity is determined by measuring rates of ³² P incorporationinto phosphorylase b using a filter paper assay (Roskoski, MethodsEnzymol. 99: 3-6, 1983, incorporated herein by reference). A reactionmixture containing 50 mM magnesium acetate, 200 μM CaCl₂, 5 mg/mlphosphorylase b, 0.9 μg/ml skeletal muscle phosphorylase kinase,calmodulin, and the test compound are combined. The mixture is incubatedat 30° C. for five minutes, and the reaction is initiated by theaddition of [γ-³² P]ATP. Phosphatase activity is assayed by determiningrates of ³² Pi release from a synthetic phosphopeptide corresponding toresidues 81-99 of bovine cardiac cAMP-dependent protein kinaseregulatory subunit. The reaction mixture contains 50 mM MOPS(4-morpholinepropanesulfonic acid) pH 7.0, 15 mM 2-mercaptoethanol, 2 mMmagnesium acetate, 2 mM MnCl₂, 0.3 μg/ml bovine braincalmodulin-dependent phosphatase, calmodulin, and the test compound. Themixture is incubated at 30° C. for five minutes, and the reaction isinitiated by the addition of ³² P-labeled peptide. Protein kinaseactivity may be assayed by determining the rate of ³² p incorporationinto chicken gizzard muscle myosin light chain using a filter papermethod (Roskoski, ibid.) in a reaction mixture of 50 mM Tris, pH 7.6,0.6 mM dithiothreitol, 0.6 mg/ml bovine serum albumin (BSA), 80 mMNaCl₁, 0.5 mM CaCl₂, 1.0 μg/ml kinase, calmodulin and test compound. Thereaction is initiated by the addition of Mg-[γ-³² P]ATP and myosin lightchain (40 μM final concentration) at 25° C. Calmodulin concentrationstypically range between 1 nM and 1 μM.

Calmodulin is believed to play a pathogenic role in the tissue damagecaused by burns and frostbite (Beitner et al., Gen. Pharmac. 2.0:641-646, 1989), as well as in dermatitis and other conditions involvingkeratinocyte hyperproliferation. The methods of the present inventionmay be applied to the treatment of these and other conditions whereinantagonism of calmodulin activity is desirable.

The following examples are offered by way of illustration, notlimitation.

EXAMPLE 1

Collodion solvent is added to pure2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran to provide afinal concentration of 100 mg per 10 ml of solvent. The solvent is amixture of three parts by volume of diethyl ether to one part by volumeof ethanol. The resulting solution is aliquotted into sterile dropperbottles. For use, the formulation is applied directly to affected skinusing a dropper in an amount sufficient to cover the affected area.

EXAMPLE 2

Soft white paraffin BP is heated to 60° C., at which point it melts.2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran is addeddirectly at a concentration of 10 mg per gram of paraffin, and themixture is thoroughly stirred. After cooling, the formulation ispackaged in sterile containers. For use, the formulation is applied byrubbing directly onto affected skin.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it will be evident that certain changes and modificationsmay be practiced within the scope of the appended claims.

What is claimed is:
 1. A method for treating dermatitis in a patientcomprising administering to a patient suffering from dermatitis aneffective amount of a composition comprising a compound of the formula##STR13## or a pharmaceutically acceptable salt thereof, wherein: eachof R1 and R2 is individually H, OH, linear or branched chain C₁ -C₁₇alkoxy, linear or branched chain C₂ -C₁₈ acyloxy, or linear or branchedchain C₂ -C₁₈ alkoxycarbonyl; andR3 is ##STR14## wherein each of R4 andR5 is individually a linear or branched chain alkyl radical of from oneto 18 carbon atoms, or together with N, R4 and R5 form a three- to10-membered ring, and n is an integer from 1 to 6, in combination with apharmaceutically acceptable carrier.
 2. A method according to claim 1wherein each of R1 and R2 is individually H, OH or C₁ -C₄ alkoxy.
 3. Amethod according to claim 1 wherein R1 is H or OH.
 4. A method accordingto claim 1 wherein R2 is H or OH.
 5. A method according to claim 1wherein each of R4 and R5 is individually methyl, ethyl, propyl,isopropyl, butyl, isobutyl, sec-butyl or tert-butyl; or together with N,R4 and R5 form a five- or six-membered ring.
 6. A method according toclaim 1 wherein R3 is ##STR15##
 7. A method according to claim 6 whereineach of R1 and R2 is individually H or OH.
 8. A method according toclaim 1 wherein said compound is ##STR16##
 9. A method according toclaim 8 wherein each of R1 and R2 is individually H or OH, and R3 is##STR17##
 10. A method according to claim 1 wherein said dermatitis is acondition selected from the group consisting of psoriasis and eczematousdermatitis.
 11. A method according to claim 10 wherein said condition ispsoriasis.
 12. A method according to claim 10 wherein said condition isatopic dermatitis, photoeczematous dermatitis, primary irritantdermatitis or allergic contact dermatitis.
 13. A method according toclaim 1 wherein said composition is in a form suitable for topicaladministration.